Influence Of Particles Research Articles

Dynamics of single cavitation bubble collapse jet under particle-wall synergy

The interaction between a particle and a cavitation bubble significantly influences the erosive effect on the wall surface of flow passage components in fluid machinery. This paper investigates the dynamics of a single bubble collapse jet under the synergetic effects of a particle and a wall, using Kelvin impulse theory and high-speed photographic experiments. A theoretical model to predict the intensity and direction of the collapse jet at arbitrary locations near the particle and the wall is constructed on the basis of the image method and Weiss's theorem. The accuracy of the model is verified by comparison with a large number of experimental results. The mechanisms underlying the relative contributions of the particle and wall to the behavior of jet intensity and direction are explored. The effects of key parameters on jet intensity and direction are also quantitatively analyzed, including the relative positions of the particle, wall, and the bubble and the dimensionless particle radius. The main conclusions are as follows: (1) the particle will cause a deflection in the direction of the collapse jet near the wall, leading to the formation of a jet attraction zone. The proposed theoretical model effectively predicts the spatial location of this zone. (2) There exists a region in which the jet is weak, and there is a jet equilibrium point with zero impulse between the particle and the wall. The position of this equilibrium point gradually approaches the wall in a nonlinear manner with increasing particle size and in a quasi-linear manner with decreasing particle–wall distance. (3) When the particle and the bubble are the same distance from the wall, the jet direction gradually changes from toward the particle to vertical to the wall in a nonlinear manner as the bubble–particle distance increases. Moreover, the effective range of the particle's influence on the jet direction decreases as the particle–wall distance decreases.

Influence of particulates on microstructure, Mechanical and Fractured behaviour on Al-7075 alloy composite by FEA

ABSTRACT Aluminium alloys are employed in advanced applications due to their desirable combination of low density, high strength, durability, availability, and cost vs. competing materials. The characteristics described above can be increased further by employing aluminium matrix composite materials reinforced with harder particles. The hybrid aluminium alloy (Al7075) composite was made in an electric resistance furnace using the sand mould process and reinforced with alumina (Al2O3) and boron carbide (B4C) particles. The purpose of this research to investigate the mechanical characteristics of Al7075-Al2O3-B4C hybrid composites with stable Al2O3 weight percentages (4%) and varied B4C weight percentages (2–6%). Mechanical characteristics includes tensile and compressive strength, hardness, and microstructure analysis were evaluated on the pure and cast specimens. In this study, which followed the ASTM standard, the mechanical characteristics of Al7075 alloy hybrid composites were examined experimentally and validated using FEA. The results showed that when hard ceramic particles (Al2O3/B4C) were added to matrix alloy (Al7075), mechanical characteristics such as compressive strength and hardness improved while tensile strength was reduced. The static structural tensile test was successfully simulated in ANSYS. It was observed that both FEA results and analytical results were correlated.

Gaining Insight into Sustainable Telecommunications Infrastructure: A Case of Aerosol Retention over Sokoto, Nigeria

The current state of aerosols retention and loading over West Africa requires urgent consideration to avert environmental disaster which include telecommunication degeneration. Research show that atmospheric aerosol leads to high light signal absorption. In this paper it is proposed that atmospheric aerosols are impactful on tropospheric radio wave propagation at a certain aerosol loading condition. Sokoto, Nigeria was considered because of its proximity to Sahara Desert. It is located on longitude 5.15°E and latitude 15.05°N on the sahelian plain. Analytical and statistical model were used to estimate the aerosols retention and loading respectively. The chaotic solution of the particulate influence on signal was numerically proven. Aerosols retention and loading effect on surface temperature was significant. The speed of the particulate distribution clearly show that atmospheric aerosols are impactful on tropospheric radio wave propagation. It was observed that tropospheric radio wave propagation depends on the volume of aerosols loading not on the attenuation due to particulate velocities. Hence, the continued signal attenuation of tropospheric radio wave propagation due to atmospheric aerosols in high prone areas must be considered during signal budgeting.

Sapphire Fiber Evanescent Wave Absorption in Turbid Media

The influence of particulates on sapphire fiber evanescent wave absorption by water has been studied. Suspensions containing micro-sized graphite flakes and glassy carbon powder were used. Conventional free-space transmittance measurements of these samples showed strong absorption and scattering, which severely screened the absorption by water. However, the absorption on the water band determined from the evanescent wave interaction was unaffected by the presence of the graphite flakes. These results indicate that fiber-optic evanescent wave chemical sensors may be suitable for process control applications involving turbid reactor streams.

Effects of particulates, heavy metals and acid gas on the removals of NO and PAHs by V 2O 5–WO 3 catalysts in waste incineration system

This study investigated the activities of prepared and commercial V 2O 5–WO 3 catalysts for simultaneous removals of NO and polycyclic aromatic hydrocarbons (PAHs) and the influences of particulates, heavy metals, SO 2, and HCl on the performances of catalysts. The experiments were carried out in a laboratory-scale waste incineration system equipped with a catalyst reactor. The DREs of PAHs by prepared and commercial V 2O 5–WO 3 catalysts were 64% and 72%, respectively. Increasing the particulate concentrations in flue gas suppressed the DRE of PAHs, but increasing the carbon content on surface of catalysts promotes the NO conversions. The DRE of PAHs by the catalysts was significantly decreased by the increased concentrations of heavy metal Cd, but was promoted by high concentration of Pb. The influence level of SO 2 was higher than HCl on the performances of V 2O 5–WO 3 catalysts for PAHs removal, but was lower than HCl for NO removal. Prepared and commercial V 2O 5–WO 3 catalysts have similar trends on the effects of particulates, heavy metals, SO 2, and HCl. The results of ESCA analysis reveal that the presences of these pollutants on the surface of catalysts did not change the chemical state of V and W.

The activity of Rh/Al 2O 3 and Rh–Na/Al 2O 3 catalysts for PAHs removal in the waste incineration processes: Effects of particulates, heavy metals, and acid gases

This study investigated the activity of Rh/Al 2O 3 and Rh–Na/Al 2O 3 catalysts for polycyclic aromatic hydrocarbons (PAHs) removal and the influence of particulates, heavy metals, and acid gases (SO 2 and HCl) on the performance of catalysts. The experiments were carried out in a laboratory-scale waste incineration system. Experimental results show that the destruction removal efficiency (DRE) of PAHs by Rh/Al 2O 3 and Rh–Na/Al 2O 3 catalysts were 80% and 59%, respectively when the flue gas did not contain any pollutants. The concentrations of PAHs increased by using a Rh/Al 2O 3 catalyst when the flue gas contained Cd, Pb, and SO 2 and also increased by using a Rh–Na/Al 2O 3 catalyst when the flue gas contained particulates, Cd, and HCl. Adding Na to the Rh/Al 2O 3 catalyst can inhibit the increases of 3–4 ring PAHs when the flue gas contained Pb. The influence of acid gases on the performance of the Rh/Al 2O 3 and Rh–Na/Al 2O 3 catalysts followed the sequence SO 2 > HCl > SO 2 + HCl. The activity of the catalysts for PAHs removal was significantly suppressed by increased concentrations in particulates and Cd, yet promoted by a high Pb concentration. The results of ESCA analysis indicated that the presence of Cd and Pb did not change the chemical states of Rh and Na, but the presence of SO 2 and HCl did.

119 マルチスケールPIVによる乱流構造に固体粒子が与える影響の計測(GS-5 流体計測(2))

119 マルチスケールPIVによる乱流構造に固体粒子が与える影響の計測(GS-5 流体計測(2))

Effects of particulates and lipids on the hydraulic conductivity of Matrigel

The hydraulic conductivity of a connective tissue is determined both by the fine ultrastructure of the extracellular matrix and the effects of larger particles in the interstitial space. In this study, we explored this relationship by examining the effects of 30- or 90-nm-diameter latex nanospheres or low-density lipoproteins (LDL) on the hydraulic conductivity of Matrigel, a basement membrane matrix. The hydraulic conductivity of Matrigel with latex nanospheres or LDL particles added at 4.8% weight fraction was measured and compared with the hydraulic conductivity of Matrigel alone. The LDL-derived lipids in the gel were visualized by transmission electron microscopy and were seen to have aggregated into particles up to 500 nm in size. The addition of these materials to the medium markedly decreased its hydraulic conductivity, with the LDL-derived lipids having a much larger effect than did the latex nanospheres. Debye-Brinkman theory was used to predict the effect of addition of particles to the hydraulic conductivity of the medium. The theoretical predictions matched well with the results from adding latex nanospheres to the medium. However, LDL decreased hydraulic conductivity much more than was predicted by the theory. The validation of the theoretical model for rigid particles embedded in extracellular matrix suggests that it could be used to make predictions about the influence of particulates (e.g., collagen, elastin, cells) on the hydraulic conductivity of the fine filamentous matrix (the proteoglycans) in connective tissues. In addition, the larger-than-predicted effects of lipidlike particles on hydraulic conductivity may magnify the pathology associated with lipid accumulation, such as in Bruch's membrane of the retina during macular degeneration and the blood vessel wall in atherosclerosis.

The Influence of Particulates on CaCO3 Scale Formation

The work reported here is based on an experimental investigation of the effect of well-defined commercial calcium carbonate particles and silica nanoparticles on the deposition rate and morphology of deposits, formed during the flow of a solution supersaturated with respect to CaCO 3 . The term combined shall be used for such runs. The effect of the above particles on the spontaneous precipitation in a supersaturated calcium carbonate solution is also examined. Isothermal conditions are maintained in all the tests

Analysis of two-phase flow processes in rocket exhaust plumes

An overview is given of the coupled two-phase flow processes occurring in rocket exhaust plumes, and modeling procedures developed to treat these processes are surveyed. The full spectrum of particle size groups encountered is modeled by a hybrid partially equilibrated mixture approach, whereby a portion of the particulaies is treated via nonequilibrium techniques. The influence of particulates on Mach disk locations and the treatment of particulate relaxation and turbulent mixing behind Mach disks is discussed in detail. A preliminary approach for treating the turbulent dispersion of particulates is presented which relates the particle diffusivity to that of the gas phase via local time scale relations. This approach is assessed via comparisons with available data extracted from the Russian literature.

Influence of particulates on infrared emission from tactical rocket exhausts

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.

Surprises at Serpukhov

Physicists construct ever more energetic particle accelerators in order to probe ever finer details of natural structures. As the energy of the probing particles has gone up, the center of attention has progressed from atoms to nuclei to the structure of such particles as protons and neutrons themselves. With each major increase in energy have come surprises, new classes of objects, new kinds of physical properties, that have forced radical changes in theory. But now, at the level of probing the structure of the so-called elementary particles themselves, some physicists have thought there ought to be a limit. Other physicists are not so sure. The latest step in the parade of energy increases is the 76-billion-electron-volt (GeV) synchrotron at Serpukhov in the Soviet Union. It is more than twice as energetic as anything that operated before it, and when it began experiments about two years ago, the question in physicists' minds was whether experimentation in this range would bring surprises or whether it would merely confirm and extend information already gathered at lower energies. The first Serpukhov experiments have already shown enough surprises to have theorists shaking their heads. Further results are now eagerly awaited. Among the first experiments were so-called total cross-section experiments intended to find out in a general way where things are at this energy range. The cross section reveals the probability that anything at all will happen when an accelerated particle is shot at a target. It depends on a wave that is associated with each particle, the socalled de Broglie wave named for Prince Louis de Broglie, who first suggested its existence in the early 1920's. The de Broglie wave is a way of measuring the probability of a particle's being somewhere in a given volume at a given time; its wavelength determines the area over which a particle's influence is felt, and the probability of some interaction with a target depends on this. At low energies the de Broglie wavelength is larger than the physical size of the particle, but as the energy goes up the wavelength decreases. Eventually a point should come where the wavelength becomes less than the physical size of the particle. At this point the total cross section becomes dependent on the size of the particle and should remain constant if the energy is further increased. But the Serpukhov results are showing that the total cross sections do not approach constant values as fast as current theory indicates they should. A related surprise is that the total cross sections for a particle and that for its antiparticle do not come together at high energies as theory says they should. At low energies the total cross sections for particle and antiparticle differ, since there are natural rules that prohibit antimatter from doing some of the things matter can do. At high energy these rules should lose their effect, and theory says the two cross sections should come to the same value, but experimentally they are not exhibiting the expected behavior. These things seem to be saying that there is something in the nature of the particles that exhibits itself at Serpukhov energies that was not taken into account in present theory, but theorists have so far not come up with an explanation. Other experiments have looked for more surprises. Serpukhov has looked for quarks, the theoretically predicted building blocks out of which the particles are supposed to be made, but has not found them. For several months the accelerator has been shut down for a rearrangement of the experimental hall and beams. When it reopens one of the first experiments will be less direct check of the quark theory than a search for quarks themselves: an investigation of negative mesons. This experiment will be done in collaboration with the CERN laboratory in Geneva as was some of the cross-section work. The quark theory says that all particles are built of either two or three subparticles called quarks, and on this basis makes predictions about their masses and other properties. Previous experiments at CERN have found a series of negatively charged mesons that fit the predictions of the quark theory especially well. The forthcoming